(1) Field of the Invention
The invention relates to fuel nozzles for combustors for gas turbine engines. More particularly, the invention relates to the configuration of the vanes of a swirler.
(2) Description of the Related Art
As is well known in the gas turbine engine technology it is desirable to operate the combustor at a combination of high efficiency, good lean blowout characteristics, good altitude relight characteristics, low smoke and other pollutant output, long life, and low cost. Scientists and engineers have been experimenting with the designs of the fuel nozzles for many years in attempts to maximize the efficacy of the combustor.
U.S. Pat. No. 5,966,937 (hereinafter the '937 patent, the disclosure of which is incorporated by reference herein as if set forth at length) discloses a swirler wherein the vanes of the inner duct have a spanwise distributed twist producing a desired swirl angle distribution at the inner duct outlet. The exemplary distribution places the vane chord closer to radial near the outboard/aft wall of the duct than near the inboard/fore wall (in an exemplary implementation, a rearward/aft direction being the downstream flow direction, which may be a rearward direction of the engine).
Nevertheless, there remains room for improvements in swirler construction.